[sci.bio] Fat Swimmers

gillies@p.cs.uiuc.edu (10/05/88)

Someone in soc.women brought up an interesting question:

"In general, world-class swimmers have a higher percentage of body fat
than almost every other type of endurance athlete.  Why is this?"

I seem to remember reading a table that said world-class marathoners
average 8.5% body fat, and swimmers average 12+% bodyfat.  Does
someone know the REAL (i.e. researched/verified/published) answer to
this question?


Don Gillies, Dept. of Computer Science, University of Illinois
1304 W. Springfield, Urbana, Ill 61801      
ARPA: gillies@cs.uiuc.edu   UUCP: {uunet,ihnp4,harvard}!uiucdcs!gillies

carey@m.cs.uiuc.edu (10/07/88)

More fat = more buoyancy.  More buoyancy less body in the water, less
drag.

It might also be a response to being in cold water all the time,
but that is speculation.

morimoto@intvax.UUCP (Alan Morimoto) (10/10/88)

From article <78300004@p.cs.uiuc.edu>, by gillies@p.cs.uiuc.edu:
> "In general, world-class swimmers have a higher percentage of body fat
> than almost every other type of endurance athlete.  Why is this?"
> 

I'm not sure that anything I am about to write has been proven by a
scientific study, but I do know that it has been observed by some scientists
that swimmers are prone to developing more fat because of the temperature of
the water they swim in.  In other words, because the water temperature is
usually much lower than body temperature, the body has a tendency to want to
protect itself from the cold by forming a layer of fat on the exterior of
the body.  Since runners usually wear plenty of clothing they don't have the
same exposure to cold and therefore do not develop this fat.


>alan
-- 
		{	Humans are the only animals that       }
		{	don't breed to improve the species.    }

			--Alan

alastair@geovision.uucp (Alastair Mayer) (10/12/88)

In article <78300004@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
[...]
>I seem to remember reading a table that said world-class marathoners
>average 8.5% body fat, and swimmers average 12+% bodyfat.  Does
>someone know the REAL (i.e. researched/verified/published) answer to
>this question?

Several reasons.  Bouyancy has already been mentioned, but the assumption
made by other posters was that this is a benefit *despite increased drag*.
Actually, a small increase in fat *decreases* drag in water.  Air drag
for a runner and water drag on a swimmer are totally different - water
is much more viscous and incompressible, so you get better drag reduction
by "filling out" to a rounded shape rather than just minimizing cross
sectional area.
   Further, thermal considerations enter into it.  Heat generated by
exertion is shed much better by a swimmer to water than by a runner
to air.  A runner *must have* less body fat to help shed heat better,
a swimmer doesn't have this problem - indeed, has an opposite problem,
needing some fat to prevent too-fast heat loss from the muscles reducing
their efficiency.

  I don't know if any of this is researched/verified/published, just
seems common sense from fluid dynamics and thermodynamics standpoint.

 -- Alastair Mayer
-------------------------------
.signature file out for refit

krista@ihlpa.ATT.COM (Anderson) (10/14/88)

woman or first person to swim across all five Great Lakes (not at
the same time).  Before crossing one of them, she was interviewed
and say that she was ready because she had gained x pounds.  She
said she expected to burn off y pounds during the swim.

    I sure wish I could remember the details, but I think x and y
were in the range of 10-20 pounds.

Krista A.

malcolm@alf.UUCP (Malcolm Colton) (10/15/88)

In article <604@intvax.UUCP> Alan Morimoto writes:
>
>I'm not sure that anything I am about to write has been proven by a
>scientific study, but I do know that it has been observed by some scientists
>that swimmers are prone to developing more fat because of the temperature of
>the water they swim in.  In other words, because the water temperature is
>usually much lower than body temperature, the body has a tendency to want to
>protect itself from the cold by forming a layer of fat on the exterior of
>the body.

I seem to recall an article in New Scientist about 15 years ago, which
described studies on the thigh fat of Londoners who wore miniskirts
and travelled by bus. They also found an increase in the fat layer,
presumably as a consequence of the exposure to cold.

Don't you wish you could get a research grant for something like this!
"Excuse me miss, I just need to measure the diameter of your upper thigh."

---------------------------------------------------------------------------
Malcolm Colton				       Sybase, Inc., Emeryville, CA
{pyramid, pacbel, sun, mtxinu, capmkt}!sybase!malcolm
___________________________________________________________________________
---------------------------------------------------------------------------
Malcolm Colton				       Sybase, Inc., Emeryville, CA
{pyramid, pacbel, sun, mtxinu, capmkt}!sybase!malcolm
___________________________________________________________________________

kenm@maccs.McMaster.CA (...Jose) (10/18/88)

>In article <78300004@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
>[...]
>I seem to remember reading a table that said world-class marathoners
>average 8.5% body fat, and swimmers average 12+% bodyfat.  Does
>someone know the REAL (i.e. researched/verified/published) answer to
>this question?
>

	Several articles have commented on why it may be helpful to 
a swimmer to have extra body fat, but any ideas on HOW they develop this?
	Do they peruposely put on the weight, or is it  
possibly a response to the prolonged exposure to cold?  I would imagine
it to be intenttionally gained... any one know better?

-----------------------------------------------------------------------------
"Fighting for Truth,                                         Kenneth C. Moyle
 Justice, and                                      Department of Biochemistry
 anything else that                 McMaster University  -  Hamilton, Ontario
 seems fun at the time"                                            kenm@maccs
-----------------------------------------------------------------------------
  

jnp@calmasd.GE.COM (John Pantone) (10/18/88)

   In article <78300004@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
   [...]
   >I seem to remember reading a table that said world-class marathoners
   >average 8.5% body fat, and swimmers average 12+% bodyfat.  Does
   >someone know the REAL (i.e. researched/verified/published) answer to
   >this question?

The various answers (speculations, most) to this query have, I think,
left out one factor - in the haste to assign cause and effect where
none may exist: Those with a higher body fat percentage are for one or
more reasons more successful at swimming - and less so at marathon
running.  The cause may well have nothing to do with swimming - but
because of this particular percentage of body fat, these people are
successful swimmers.

Don't forget that correlation does not imply cause/effect!

-- 
These opinions are solely mine and in no way reflect those of my employer.  
John M. Pantone @ GE/Calma R&D, 9805 Scranton Rd., San Diego, CA 92121
...{ucbvax|decvax}!sdcsvax!calmasd!jnp   jnp@calmasd.GE.COM   GEnie: J.PANTONE

binkley@boulder.Colorado.EDU (Jon Binkley) (10/18/88)

In article <1504@maccs.McMaster.CA>, kenm@maccs.McMaster.CA (...Jose) writes:

>>In article <78300004@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
>>[...]
>>I seem to remember reading a table that said world-class marathoners
>>average 8.5% body fat, and swimmers average 12+% bodyfat.  Does
>>someone know the REAL (i.e. researched/verified/published) answer to
>>this question?
>>

>	Several articles have commented on why it may be helpful to 
>a swimmer to have extra body fat, but any ideas on HOW they develop this?
>	Do they peruposely put on the weight, or is it  
>possibly a response to the prolonged exposure to cold?  I would imagine
>it to be intenttionally gained... any one know better?

I don't know better, but as long as we're still imagining here...

I would imagine that it's selected for unintentionally.  Someone with
not much body fat would not be as good a swimmer as someone with
"enough" body fat (for the buoyancy and hydrodynamic reasons already
imagined here) and would therefore never become "world-class".

Jon Binkley

marb@tank.uchicago.edu (marty e billingsley) (10/19/88)

In article <1504@maccs.McMaster.CA> kenm@maccs.UUCP (...Jose) writes:
>>In article <78300004@p.cs.uiuc.edu> gillies@p.cs.uiuc.edu writes:
>>[...]
>>I seem to remember reading a table that said world-class marathoners
>>average 8.5% body fat, and swimmers average 12+% bodyfat.  Does
>>someone know the REAL (i.e. researched/verified/published) answer to
>>this question?
>
>	Several articles have commented on why it may be helpful to 
>a swimmer to have extra body fat, but any ideas on HOW they develop this?
>	Do they peruposely put on the weight, or is it  
>possibly a response to the prolonged exposure to cold?  I would imagine
>it to be intenttionally gained... any one know better?
>
>     - Kenneth C. Moyle


Well, speaking from personal experience, I can say that the fat is *not* 
intentionally gained.  I have always been a runner (competed in college).  My 
sister has always been a swimmer (also competed in college).  Both of us are 
very similar, except when it comes to body shape.  Although we're the same
height and have the same type of bone structure, I am heavier than she is,
have bigger legs, and a lower fat percentage (8% usually).  My sister
has smaller legs, much bigger shoulders, but a layer of fat, especially on her
upper body, that she can't get rid of.  Her body fat has never been below
11%, although she works out a *lot* more than I do, and eats a lot better than 
I do (lots of pasta and no sweets).

I tend to agree that fat is gained for both insulation and buoyancy purposes.
When I swim, I freeze to death (it would help if I put on some fat).  Also,
when I wear a wet suit, I go substantially faster than without.  So the 
buoyancy does help you go faster.

An interesting note: since my sister has started runing some, she's dropped 
some of her fat - mostly from the shoulders.  So I would say that the body
knows what it's doing when it decides to get fat and when it decides to get
skinny.

  - Marty   

P.S. For the purpose of this discussion, it is important to realize that 
     I am a female.

-- 
"Haven't you got anything?"                    |  Marty Billingsley         | 
"Sorry.  Not on me."                           |  marb@sphinx.uchicago.edu  |
"We could stop at your cash machine."          ------------------------------
"We could," he agreed, "but it would only be a social call."

wjh@inf.rl.ac.uk (Bill Hewitt) (11/23/88)

In article <20800004@m.cs.uiuc.edu> carey@m.cs.uiuc.edu writes:
>
>More fat = more buoyancy.  More buoyancy less body in the water, less
>drag.
>
>It might also be a response to being in cold water all the time,
>but that is speculation.


Why is the original article comparing swimmers to long distance runners ?
The longest racing distance for a swimmer is 1500m This will take a
leading swimmer somewhere in the region of 15 minutes to complete. This is
not a fair comparison with the 2 hours it takes to complete a marathon !

-- 
Bill Hewitt,                                 UUCP:  ..!mcvax!ukc!rlinf!wjh
Science & Engineering Research Council,      JANET:  wjh@uk.ac.rl.inf
Rutherford Appleton Laboratory,
Chilton, Didcot, 
Oxfordshire, OX11 0QX.             
U.K.                                           Tel: (0235) 44 6713       

If no one seems to understand start your own revolution cut out the middle man !

wjh@inf.rl.ac.uk (Bill Hewitt) (11/28/88)

In article <1510@sybase.sybase.com> malcolm@alf.UUCP (Malcolm Colton) writes:
>In article <604@intvax.UUCP> Alan Morimoto writes:
>>
>>I'm not sure that anything I am about to write has been proven by a
>>scientific study, but I do know that it has been observed by some scientists
>>that swimmers are prone to developing more fat because of the temperature of
>>the water they swim in.  In other words, because the water temperature is
>>usually much lower than body temperature, the body has a tendency to want to
>>protect itself from the cold by forming a layer of fat on the exterior of
>>the body.
>
>I seem to recall an article in New Scientist about 15 years ago, which
>described studies on the thigh fat of Londoners who wore miniskirts
>and travelled by bus. They also found an increase in the fat layer,
>presumably as a consequence of the exposure to cold.
>
>Don't you wish you could get a research grant for something like this!
>"Excuse me miss, I just need to measure the diameter of your upper thigh."
>
>---------------------------------------------------------------------------
>Malcolm Colton				       Sybase, Inc., Emeryville, CA
>{pyramid, pacbel, sun, mtxinu, capmkt}!sybase!malcolm
>___________________________________________________________________________
>---------------------------------------------------------------------------
>Malcolm Colton				       Sybase, Inc., Emeryville, CA
>{pyramid, pacbel, sun, mtxinu, capmkt}!sybase!malcolm
>___________________________________________________________________________


Or is it that girls with skinny legs and knobbly knees don't ware miniskirts
:-)

-- 
Bill Hewitt,                                 UUCP:  ..!mcvax!ukc!rlinf!wjh
Science & Engineering Research Council,      JANET:  wjh@uk.ac.rl.inf
Rutherford Appleton Laboratory,
Chilton, Didcot, 
Oxfordshire, OX11 0QX.             
U.K.                                           Tel: (0235) 44 6713       

If no one seems to understand start your own revolution cut out the middle man !

wjh@inf.rl.ac.uk (Bill Hewitt) (11/28/88)

In article <1510@sybase.sybase.com> malcolm@alf.UUCP (Malcolm Colton) writes:
>In article <604@intvax.UUCP> Alan Morimoto writes:
>>
>>I'm not sure that anything I am about to write has been proven by a
>>scientific study, but I do know that it has been observed by some scientists
>>that swimmers are prone to developing more fat because of the temperature of
>>the water they swim in.  In other words, because the water temperature is
>>usually much lower than body temperature, the body has a tendency to want to
>>protect itself from the cold by forming a layer of fat on the exterior of
>>the body.
>
>I seem to recall an article in New Scientist about 15 years ago, which
>described studies on the thigh fat of Londoners who wore miniskirts
>and travelled by bus. They also found an increase in the fat layer,
>presumably as a consequence of the exposure to cold.
>
>Don't you wish you could get a research grant for something like this!
>"Excuse me miss, I just need to measure the diameter of your upper thigh."



Or is it just that girls with skinny legs and knobbly knees do not choose to
wear miniskirts ;-)

-- 
Bill Hewitt,                                 UUCP:  ..!mcvax!ukc!rlinf!wjh
Science & Engineering Research Council,      JANET:  wjh@uk.ac.rl.inf
Rutherford Appleton Laboratory,
Chilton, Didcot, 
Oxfordshire, OX11 0QX.             
U.K.                                           Tel: (0235) 44 6713       

If no one seems to understand start your own revolution cut out the middle man !

malcolm@alf.UUCP (Malcolm Colton) (12/06/88)

In article <4439@rlvd.UUCP> wjh@inf.rl.ac.uk (Bill Hewitt) writes:
>>
>>I seem to recall an article in New Scientist about 15 years ago, which
>>described studies on the thigh fat of Londoners who wore miniskirts
>>and travelled by bus. They also found an increase in the fat layer,
>>presumably as a consequence of the exposure to cold.
>>
>Or is it that girls with skinny legs and knobbly knees don't ware miniskirts
>:-)
>
I considered this, but at the time, (remember Twiggy) miniskirts were
almost compulsory for young fashion-conscious women. I suspect that women
wore them even though they felt considerable discomfort. Even chubby
thighs are not much protection when you are waiting by the bus stop!
Of course to validate this, one would like a control study of women who
wore longer skirts. While my fantasy goes that far, my memory does not.
----------------------------------oOo---------------------------------------
If you think this is Corporate policy, I have a bridge you might like to buy
Malcolm Colton				       Sybase, Inc., Emeryville, CA
{pyramid, pacbel, sun, mtxinu, capmkt}!sybase!malcolm

stevev@uoregon.uoregon.edu (Steve VanDevender) (12/09/88)

In article <4387@rlvd.UUCP> wjh@inf.rl.ac.uk (Bill Hewitt) writes:
>Why is the original article comparing swimmers to long distance runners ?
>The longest racing distance for a swimmer is 1500m This will take a
>leading swimmer somewhere in the region of 15 minutes to complete. This is
>not a fair comparison with the 2 hours it takes to complete a marathon !

While competitive swimming races are quite short, the amount of
training that a competitive swimmer can put in is really remarkable.
I have heard of Olympic swimmers spending four or more hours in the
pool each day, swimming the whole time.  This compares quite well with
the amount of training put in by long distance runners.  And it might
also explain why swimmers' bodies would put on a thicker fat layer,
since they spend enough time in the water to make it pay off.

I swim largely for exercise and have been known to put in eight miles
a week when it was my only activity.  Now that I've taken up wheelchair
racing and weight training to improve my 'chair racing, I barely manage
half that much distance now.  I can tell that swimming takes at least
as much endurance and is probably a better cardiovascular exercise than
wheelchair road-racing, though.


-- 
Steve VanDevender 	stevev@drizzle.cs.uoregon.edu	stevev@oregon.BITNET
"Bipedalism--an unrecognized disease affecting over 99% of the population.
Symptoms include lack of traffic sense, slow rate of travel, and the
classic, easily recognized behavior known as walking."